The present invention relates to an inhibitor of an activation of .beta.-glucan recognition protein in a body fluid of an insect, a process for inhibiting the activation; an agent for treating a body fluid of an insect, a process for the treatment; a novel agent for measuring peptidoglycan, and a process for the measurement.
Peptidoglycans (hereinafter abbreviated as PG) are glycoprotein containing N-acetylmuramic acid residue or N-glycolylmuramic acid residue and D-amino acid residues, and they play, as bacterial cell wall components, an important role for retention of the form of bacteria.
PG have various biological activities such as various functions to immune response cells (e.g. macrophages, B lymphocytes, T lymphocytes, etc.), destruction of blood platelets, growth enhancement of fibroblasts, enhancement of bone resorption, activation of complements, enhancement or inhibition of humoral immune responses, enhancement of cellular immunity, stimulation of cell endotherial systems, transient leukopenia and subsequent hypercytosis, enhancement of the functions of interferon inducing factors, potentation of natural resistance, induction of experimental autoimmune diseases, pyrogen functions, enhancement of sensitivity to the toxicity of endotoxins (hereinafter abbreviated as ET), enhancement or inhibition of sleep, formation of epithelioid granulomas, functions of hemorrhagic necrosis at sites treated with tubercle bacillus or the like and acute or chronic toxicity.
While ET are contained only in Gram-negative bacteria, PG are contained both in Gram-positive bacteria and Gram-negative bacteria. And PG are contained in the cell walls to form thick layers at the outermost shells of cell walls in the Gram-positive bacteria, and are contained in the cell walls to form thin layers inside outer membranes of the cell walls in the Gram-negative bacteria. Almost all procaryotes contain PG in their cell walls except for archaebacteria (e.g. methane bacteria, highly acidophilic bacteria, etc.) which contain neither ET nor PG. On the other hand, PG are not contained in the cell components of eukaryotes such as mammals and hence it is considered that bacteria are present where PG is present.
Therefore, PG measurement is useful for detecting a trace amount of microorganisms such as bacteria and blue-green algae (Cyanophyceae) , which contain PG as a constituent of cell wall, and is expected to be applicable to, for example, safety tests of drugs and the like, microbial tests of water and foods, and diagnoses of infectious diseases.
As a process for measuring PG, there has been reported, for example, a method using a reagent derived from a body fluid of an insect (JP-B 7-114707). The body fluid of an insect contains factors constituting the pro-phenol oxidase (hereinafter abbreviated as proPO) cascade, and usually, they are not yet activated (inactive type factors). The body fluid of an insect contains, as one of the factors, a substance which binds to PG to activate the proPO cascade (PG recognition protein). The process for measuring PG mentioned above is characterized in utilizing such property of PG contained in the sample as binding to this PG recognition protein in a body fluid of an insect to activate the proPO cascade. However, the body fluid of an insect also contains substance which binds to .beta.-1,3-glucan (hereinafter abbreviated as .beta. G) to activate the proPO cascade ( .beta. G recognition protein, which is hereinafter abbreviated as .beta. GRP) [Yoshida, H., Ochiai, M., and Ashida, M. (1986) Biochem. Biophys. Res. Commun. 141, 1177-1184]. So, in the process mentioned above, it is necessary to remove .beta. GRP from the body fluid of an insect before making it into the reagent to measure the PG specifically by affinity chromatography or the like, and this removing process is complicated and troublesome.